1. Field of the Invention
The present invention describes a method for producing an aqueous silicone emulsion composition.
2. Background Information
Various aqueous silicone emulsion compositions yielding rubbery elastomers after the removal of water have been proposed or provided for the treatment of fiber and paper and for use as a waterproofing paint film for concrete, wood or slate, etc., based on the excellent water repellency, weather resistance and rubbery elasticity of silicones. For example, Japanese Kokai [Laid Open] Pat. No. 56-16553 [81-16553], equivalent to U.S. Pat. No. 4,221,688, issued Sept. 9, 1980, proposes an aqueous silicone emulsion composition which is principally composed of a hydroxyl-terminated diorgano-polysiloxane, colloidal silica and an alkyltin salt. The addition of an extender filler to said emulsion composition produces a paint film material which readily gives a thick coat in a single application or produces a filler for cracks, gaps or joints, etc. Examples of the extender fillers which can be employed for this purpose are clay, aluminum oxide, quartz, calcium carbonate, zinc oxide and mica.
Japanese Kokai Pat. No. 58-118853 [83-118853], equivalent to U.S. Pat. No. 4,427,811, issued Jan. 24, 1984, describes an improved method for producing high-solids silicone elastomer emulsions.
As discussed above, it is known that thick-coating paints and caulks, etc., may be produced by the addition of an extender filler to an aqueous silicone emulsion in order to raise the solids content.
However, when an aqueous silicone emulsion composition containing a large quantity of filler in order to raise the solids content or viscosity is used as a sealing agent for filing gaps, joints, etc., the problem arises that it peels at the interface during the curing process, specifically from coated porous surfaces. This phenomenon is peculiar to porous surfaces and does not occur at flat smooth surfaces of metal, glass, etc. Since various porous materials such as mortar, slate and wood, etc., are used in civil engineering structures and buildings, it is very important that high-solids aqueous silicone emulsion compositions not peel from such porous materials.
Various methods were examined by the present inventors in order to eliminate the above-mentioned drawback to prior high-solids aqueous silicone emulsion compositions and the present invention was developed as a result. That is, the goal of the present invention is to provide a high-solids aqueous silicone emulsion composition which does not peel at the interface when applied to porous materials, either during or after the curing process.